What defines latent tuberculosis?

Latent tuberculosis is characterized by an inactive infection where the bacterium Mycobacterium tuberculosis remains in the body without causing any symptoms or being transmissible to others. In this state, the immune system is able to contain the bacteria, preventing them from causing active disease while still maintaining a presence in the body.

Individuals with latent tuberculosis might test positive on a tuberculin skin test or an interferon-gamma release assay, but they do not exhibit the clinical signs and symptoms associated with active tuberculosis, such as cough, fever, or weight loss. This inactive state may remain for years and could potentially reactivate under certain conditions, like if the person's immune system becomes weakened.

In contrast, active infections manifest with clear symptoms and require more urgent medical intervention. Chronic conditions usually denote long-term or persistent issues rather than the specific inactive status of latent TB. Similarly, a recent infection would not align with the definition of latent TB, as that suggests an active or developing infection rather than an dormant one.